1 Field of the Invention
The present invention generally relates to a method of selective oxidation, and more particularly, the present invention relates to a method for forming an isolation region.
This application is a counterpart of Japanese application Serial Number 238467/1997, filed Sep. 3, 1997, the subject matter of which is incorporated herein by reference.
2 Description of the Related Art
In general, a local oxidation (LOCOS) method has been used in the formation of an isolation region.
FIGS. 1A-1D are sectional views showing a conventional method of selective oxidation.
As shown in FIG. 1A, a silicon oxide film 12 is formed on a silicon substrate 10 using a thermal oxidation method. A silicon nitride film 14 is formed on the silicon oxide film 12 using a low-pressure chemical vapor deposition (LP-CVD) method.
As shown in FIG. 1B, the silicon oxide film 12 and the silicon nitride film 14 are patterned so as to remain on a plurality of active regions (not shown) defined on the silicon substrate 10 using a photolithography technique and an etching technique, and as a result the silicon oxide film patterns 12a and the silicon nitride film patterns 14a are formed on each active region of the silicon substrate 10.
As shown in FIG. 1C, a plurality of field oxide films 16 are formed on each isolation region defined on the silicon substrate 10 between the active regions using a thermal oxidation technique.
As shown in FIG. 1D, the silicon oxide film patterns 12a and the silicon nitride film patterns 14a are removed from the silicon substrate 10.
In the conventional method, it is desirable to prevent a problem of a lateral oxidation producing a so-called bird's beak during selective oxidation of the silicon.